This thesis proposes the design of a multi-user architecture for Lunar proximity communication links, with a focus on Data Link Layer and Physical Layer multiplexing techniques. The core of the work is the design and validation of the strategies adopted at the Physical Layer. The study is part of ANDROMEDA, a Lunar communication service based on a constellation of microsatellites designed by the Italian aerospace company Argotec. After a brief description of ANDROMEDA’s baseline architecture and concept of operations, the definition of system requirements to support multi-user communications follows. The protocol stack is then defined with a description of involved Consultative Committee for Space Data System (CCSDS) Standards and a couple of use cases are also presented.